Circular No. 7217
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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GRB 990704
     J. Heise and J. in 't Zand, Space Research Organization of the
Netherlands (SRON), Utrecht; G. Celidonio, G. Scotti, and G.
Gandolfi, BeppoSAX Science Operation Center, Telespazio, Rome; M.
Feroci, P. Soffitta, and L. Piro, Istituto di Astrofisica Spaziale
(IAS), CNR, Rome; and E. Palazzi and L. Amati, Istituto Tecnologie
e Studio Radiazioni Extraterrestri (ITESRE), Bologna, report:  "A
gamma-ray burst with a bright x-ray counterpart triggered the
BeppoSAX Gamma-Ray Burst Monitor (GRBM) on July 4.7294 UT and was
simultaneously detected in the Wide Field Camera (WFC) unit 1.  The
burst lasted for about 40 s in the 2-26-keV WFC data and had three
peaks with increasing intensity.  The WFC peak intensity
corresponds to a flux of 6.2 Crab.  The 40-700-keV GRBM flux is
weak and has a similar duration.  A peak of 320 counts/s is
coincident with the maximum intensity in the WFC.  The WFC-
determined position and error circle of the x-ray counterpart to
GRB 990704 is as noted on IAUC 7214 (99-percent confidence level),
which includes a potential 4' error in the satellite attitude."
     M. Feroci and G. Gandolfi, IAS, Rome; L. A. Antonelli,
Osservatorio Astronomico di Roma; M. R. Daniele, C. De Libero, L.
Di Ciolo, and V. Torroni, BeppoSAX, Rome; F. Frontera, ITESRE, CNR,
Bologna; and J. Heise, SRON, report on behalf of the BeppoSAX Team:
"The BeppoSAX Narrow Field Instruments observed the region of GRB
990704 from July 5.064 to 5.989 UT.  One previously unknown x-ray
source (1SAX J1219.5-0350) was found inside the 7' BeppoSAX WFC
error circle at R.A. = 12h19m27s.3, Decl. = -3 50'22" (equinox
2000.0, error radius 1', 90-percent confidence level).  The average
source flux at 2-10 keV was (8.0 +/- 0.6) x 10**-3 counts/s,
corresponding to about 4.4 x 10**-13 erg cm**-2 s**-1, assuming a
power-law spectrum.  The source shows a fading behavior, strongly
suggesting that it is the x-ray afterglow of GRB 990704."
     Regarding their report on IAUC 7214, A. Maury et al. write:
"We have observed the field of GRB 990704 again during the night of
July 5-6.  The optical object reported on IAUC 7214 is still
visible at the same position and seems to be not variable (see also
GCN 367, 370, 371); it is therefore very likely not the optical
counterpart of GRB 990704."

                      (C) Copyright 1999 CBAT
1999 July 6                    (7217)            Daniel W. E. Green